"I had this beautiful idea. Might have gotten carried away with ourselves. Artists are prone to that thing. A drop of megalomania, a touch of generosity, a dash of self-promotion, and deep fear that these songs that we poured our life into over the last few years might not be heard," he added.

"There's a lot of noise out there. I guess, we got a little noisy ourselves to get through it."

Thanks to Apple, people can now remove the album from their iTunes accounts with the click of an on-screen icon.

U2 -- who released some of the most acclaimed albums of the 1980s including "The Joshua Tree" and "Rattle and Hum" -- could have expected major sales for a new album.

While Apple did not disclose financial arrangements for the free release, U2 has collaborated for years on products with the company.